In the 1970s, it was reported that silicon was an important trace element for the formation and mineralization of bone. Silicon was shown to localize to active calcification sites in bone in young mice and rats. Chickens and rats maintained on a silicon-deficient diet had impaired collagen synthesis and defective skeletal structure (Carlisle, Edith M. [1970] Science 167:279-280; Carlisle, E. M. [1976] J. Nutr. 106:478-484).
More recently, the proosteogenic properties of a class of silicon-containing compounds, the zeolites, have been studied. Zeolites have been employed widely as catalysts in the petrochemical industry and as components of detergents. They are composed of (SiO4) and (AlO4) tetranedra, which share oxygen-bridging vertices and form cage-like structures in crystalline form. The addition of a synthetic zeolite, sodium zeolite A, to chicken feed increased eggshell thickness and protected the eggs from breakage. As with bone, the process of eggshell formation involves the synthesis of a mineralizable matrix. Also, a single injection of zeolite A into incubating chicken eggs resulted in dose-dependent increases in diaphyseal cortical bone of the hatchling.
Over the years a wide variety of experiments have been conducted throughout the world utilizing zeolites of many different types in the feeding of animals for varying reasons. Most of these experiments have been in the fields of animal nutrition or animal husbandry, e.g. in increasing the production of food animals or their food products. Animals fed zeolites were poultry, cattle, sheep and swine. Zeolites fed to the animals were mainly naturally occurring zeolites.
Keeting et al. (Keeting, Philip E., Merry Jo Oursler, Karl E. Wiegand, Susan K. Bonde, Thomas C. Spelsberg, B. Lawrence Riggs [1992] J. of Bone and Mineral Res. 7(11), Mary Ann Liebert, Inc., Publishers) showed that silicon in trace amounts enhances bone formation, and the silicon-containing compound Zeolite A increases eggshell thickness in hens. Zeolite is a SiO4xe2x80x94AlO4 cage-like structure. Zeolite induces gene expression and release in the osteoblast-like cells of latent transforming growth factor (TGF-xcex2). In many tissues, including bone, TGF-xcex2 is secreted as a latency complex containing one or more binding proteins.
Experiments conducted in Japan on the use of natural zeolite minerals as dietary supplements for poultry, swine and cattle reported significant increases in body weight per unit of feed consumed and in the general health of the animals; (Minato, Hideo, Koatsugasu 5:536, 1968). Reductions in malodor were also noted. Using clinoptilolite and mordenite from northern Japan, Onagi, T. (Rept. Yamagata Stock Raising Inst. 7, 1966) found that Leghorn chickens required less food and water and gained as much weight in a two-week trial as birds receiving a control diet. No adverse effects on health or mortality were noted. [F. A. Mumpton and P. H. Fishman, Journal of Animal Science, Vol. 45, No. 5 (1977), pp. 1188-1203].
Other studies indicate that zeolite A has a positive effect upon structural maintenance and strength of bone within six weeks of administration and that zeolite A in poultry diets causes a reduced incidence and severity of tibial dyschondroplasia (osteochondrosis) and enhanced absorption of 47Ca [Edwards, Annual Meeting of the Poultry Science Assoc., North Carolina State University (1986)]. Research of Laurent et al has also resulted in the discoveries that zeolite A (i) decreases mortality in the rate of laying hens, U.S. Pat. No. 4,610,883 (incorporated by reference in its entirety); Roland et al, J. Poultry Sci., 64:1177 (1985), Miles et al, Nutrition Reports International (1986); (ii) increases quality of poultry eggshells, U.S. Pat. No. 4,556,564 (incorporated by reference in its entirety); (iii) and reduces heat stress. It has also been discovered that zeolite A inhibits kidney stones or urinary calculi in lambs [U.S. Pat. No. 4,515,780 (incorporated by reference in its entirety)].
Vitamins and minerals are necessary for normal metabolic functioning of both humans and animals. Vitamins are either fat-soluble or water-soluble. The use of vitamin and mineral supplements to compensate for deficiencies thereof in animals and humans due to age, poor eating habits or genetic defects is known in the art.
In particular, equine are known to suffer from a number of conditions related to vitamin and minerals deficiencies due to poor quality forage or hay, chronic colic, chronic diarrhea, or anorexia resulting from dental disease. In addition, there may also be disturbances in absorption as the result of liver or biliary tract disease, hypothyroidism, anemia and other pathological conditions of the digestive system and related organs. Numerous equine supplements are currently on the market.
A horse is generally feed-restricted or hand-fed at least twice per day due to its small stomach size relative to its large body mass. Feeding a horse in an unrestricted or xe2x80x9cad libitumxe2x80x9d fashion often results in colic, founder, azoturia and other digestive related problems. To avoid such problems, even complete horse rations containing roughage must be carefully hand-fed. Manual feeding is often time consuming and costly, especially for owners of pleasure horses.
It is known in the art to produce horse feeds for high performance horses which have compositions exhibiting good palatability, improved digestibility and high carbohydrate content for increased energy. Such feeds are described in, for example, U.S. Pat. Nos. 3,946,115; 4,166,867; and 4,197,320 (hereby incorporated by reference in their entireties). These patents describe rations which are designed to supplement an existing diet. Dietary supplements have also been described for ruminants, e.g., in U.S. Pat. Nos. 4,197,319 and 4,230,736, hereby incorporated by reference in their entireties.
Osteoporosis is a metabolic bone disease characterized pathologically by an absolute decrease in the amount of bone, and clinically by increased susceptibility to fractures. Riggs et al., N. Engl. J. Med. (1986), 314:1676; Rusbach et al., In: Textbook of Endocrinology, Ed(s) Williams, (1981), p. 922; Riggs, In: Cecil Textbook of Medicine, Ed(s) Wyngaarden et al., (1985), p. 1456; Riggs et al., Am. J. Med., (1983), 75:899.
In post-menopausal women, estrogen deficiency has been identified as a major predisposing factor. Recent studies in normal women ages 20 to 88 years indicate, however, that substantial bone loss from the axial skeleton occurs gradually in the decades before estrogen deficiency ensues at menopause. Riggs et al., J. Clin. Invest., (1986), 77:1487. According to Riggs et al., xe2x80x9c . . . factors in addition to estrogen deficiency must contribute to the pathogenesis of involutional osteoporosis in women because about half of overall vertebral bone loss occurs premenopausally.xe2x80x9d
Calcium deficiency is believed to be one of those additional factors. Riggs, In Cecil Textbook of Medicine, Id.; Nordin, (1985), Lancet 2:720; Fujita, (1986), 12:49; Heaney, In: Osteoporosis II Ed(s), Bonzel, (1979), p. 101; and Heaney, (1982), J. Lab. Clin. Med. 100:309. Three conditions, in turn, have been identified as predisposing to calcium deficiency: suboptimal calcium intake, subnormal intestinal calcium-absorptive ability and normal or above average protein intake, Heaney, In Osteoporosis II, Id.; Heaney et al., (1982), Am. J. Clin. Nutr. 36:986.
An increasing demand on body calcium stores is imposed by increasing dietary protein, which increases urinary excretion of calcium. Lutz, Id.; Schuette, et al., (1982), J. Nutr. 112:338; Lutz, et al., (1981), Am. J. Clin. Nutr., 34:2178; Hegsted, et al., (1981), J. Nutr. 111:553; Schuette, et al., (1980), J. Nutr. 110:305; Allen, et al., (1979), 32:741; and Margen, et al., (1974), Am. J. Clin: Nutr. 27:584. Intestinal absorption of calcium fails to increase commensurately with protein-induced calciuria, hence external calcium balance becomes negative. Lutz, Id.; Schuette, et al., (1982), Id. In combination, low dietary intake of calcium and high dietary intake of protein result in greater calcium deficiency than does either condition alone. Lutz, Id.; and Rekha, et al., 1974, J. Nutr. 104:695.
There remains a need for nutritional supplements for humans and other animals which can improve health. This improvement can be, for example, improved weight gain, bone strength, and/or, in the case of birds, improved shell strength of eggs.
The subject invention provides materials and methods for improved nutrition. Specifically exemplified herein is the use of dietary or nutritional supplements which comprise bioactive glass. In a preferred embodiment, the bioactive glass is powdered. These supplements are useful in both veterinary and human contexts. Dietary supplements comprising a bioactive material, BIOGLASS(copyright) for example, are attractive dietary supplements for a variety of reasons. Advantageously, bioactive glass is much more soluble than zeolite compounds. Furthermore, bioactive glass is also capable of carrying nutrients to the desired target sites and many forms of the glass are resorbable.
One embodiment of the subject invention contemplates methods of enhancing the growth rates of young (not mature) animals by the administration of nutritional supplements containing powdered bioactive glass or the administration of feeds containing bioactive glass.
Another embodiment of the invention contemplates the osteogenic stimulation in animals by administration of nutritional supplements comprising powdered bioactive glass or the administration of feeds.
Another embodiment of the invention is drawn to methods of strengthening the skeletal structure of an animal comprising the administration of powdered bioactive glass to an animal through dietary supplements or the normal course of feeding.
The subject invention also contemplates novel methods for treating osteoporosis and, more particularly, involves the administration of pharmaceutically acceptable dietary or nutritional supplements comprising powdered bioactive glass. The powdered bioactive glass may also be incorporated into or added to meals and beverages. Pharmaceutical compositions comprising powdered bioactive glass and other nutritive or dietary supplements are also contemplated.